The acetylcholine receptor (AchR) depolarizes the post-synaptic neuromuscular junction by increasing membrane cation permeability in response to binding of acetylcholine. This work involves an attempt to incorporate the AchR into phospholipid bilayers and reconstitute the ion permeability know to be appropriate for the receptor in vivo. AchR used in these studies comes from two sources: (1) Torpedo ocellata electroplax receptor purified by alpha-cobrotoxin affnity chromatography in the laboratory of Dr. M. Eldefrawi, and (2) from mammalian skeletal muscle. The skeletal muscle AchR is prepared by gel filtration on Sepharose 6B and affinity chromatography using alpha-cobrotoxin. We are currently attempting to reconstitute T. ocellata AchR into phospholipid vesicles and planar phospholipid bilayers. Preliminary efforts have resulted in incorporation of receptor into vesicles, but it has not yet been possible to show cholinergic drug-sensitive conductance changes in either vesicles or planar bilayers. Skeletal muscle AchR preparations show large conductance changes that are stimulated by acetylcholine, and blocked by curare and alpha-bungarotoxin.